Safety installation for grade crossings



sept. 25, 1928. 1,685,480

T. E. CLARK SAFETY INSTALLATION FOR GRADE CROSSINGS A ORNEY sept 25, 1928.

T. E. CLARK SAFETY INSTALLATION FOR GRADE CROSSINGS Filed March 25, 1927 2 Sheets-Sheet 2 NvEN o R BH3 n'TORNEY Patented Sept. 25, 1928.

UNITED STATES APATENT OFFICE.

THOMAS E. CLARK, OF DETROIT, MICHIGAN, ASSIGNOR TO CONTINUOUS TRAIN CON- l TROL CORPORATION, OF DETROIT, MICHIGAN, A CORPORATION OF MICHIGAN.

SAFETY INSTALLATION FOR GRADE CROSSINGS.

Application iled March 25, 1927. Serial No. 178,240.

This invention relates to means designed to reduce the number of accidents which occur at the crossings of highways and railway tracks because the drivers of automobiles do not realize the approach of trains, and its object is to provide means at such crossings to impart proper electric signals to the automobiles and to provide means on the automobiles to respond to such signals.

This invention consists in an electric installation positioned at a railway and highway crossing, and means whereby such installat-ion is caused to operate upon the approach of a railway train, and of a high-frequency current transmitting meansv positioned a proper distance from such crossing and preferably embedded in the roadway.

It also consists in signals at points on the highway a. distance from the crossing to designate the approach of trains.

It also consists of electro-responsive means adapted to be mounted on automotive vehicles, which, when said current transmitting means along the highway are functioning, will respond thereto either by causing a signal on the vehicle to be energized, or the circuit for the ignitioncurrent of the automobile engine to be opened, or the automobiles brakes to be applied, or to cause either two or all of these acts to occur simultaneously.

It also consists of means for notifying the engineer of the approaching train, either by audible orvisible signal or both, that he is approaching such a crossing. i

lt Jfurther consists in the details of construction illustrated in the accompanying drawings and particularly pointed out in the claims.

In the accompanying drawings, Fig. l is a diagram of an electric trackway installation for controlling the operation of automobiles at crossings; Fig. 2 is a diagram of an automobile installation adapted to respondthereto; Fig. 3 is a diagram of another automobile installation; Fig. 4 is a diagram of a modified form of trackway installation; Fig. 5 is a diagram of a locomotive installation adaptled to respond thereto; and Fig. 6 is a perspective view showing conductor wires embedded in a roadway slab.

Similar reference characters refer to like parts throughout the several views.

While the word locomotive is used in this application to designate the vehicle on the track rails, it should be understood that this term is intended to include self-propelling rail-vehicles of all kinds.

The tmclcwy installation.

In the drawings, the pairs of rails l and 2, 3 and 4 ot' a double track are indicated as divided into blocks by means of insulations 5 and to each block at its entrance end is' connected a track-battery 6, and adjacent the crossing highway is a control relay 7-8. The control current is derived directly from an electron tube 9 .whose filament is heated by current from the battery 1() when either of the tracks of the adjacent block are occupied. In the present case a train T occupies the east-bound track, resulting in the short-circuiting of the relay 7. Current now passes from the battery 10 over wires 12 and 13, armature 14, wires and 16, filamentvof tube 9 and wires 17 and 18 t-o the battery. It the other track were occupied, the armature 19 of relay 8 would have closed this circuit.

The plate circuit of this tube 9 includes the battery 20, wire 21, plate coil 22, wire 23 to the plate, and on theother side, the wires 24, 25 and 17 to the filament. The grid coil 26 connects to the wire 25 and to the grid by the wire 27, while it connects to the ends of the plate coil 22 by means of condensers 28.

The `high-frequency current output coil 30 connects to the roadside inductor loop 38 by means of wire 32, primary winding 33 of a signal-control inductan'ce, and wires 34 and 35, while it connects to the other roadside inductor loop 39 by means of the wire 36, a condenser 37 being installed to tune the output circuit. The loops are connected by wire 31 to complete the circuit. Whenever, therefore, either of the tracks is occupied, highfrequency current will pass to the inductor loops 38 and 39, one at each side of the railway track.

Signal lamps along the roadway and rail way tracks are controlled by a relay 41 having an armature 42. This relay is energized by induced current in the secondary winding 43 when the primary winding 33 receives current, this current being rectified by the radiofrequency rectifier 44 of any desired construction, the relay being connected to the winding 43 by wire 45 on one side und the wires 46 and 47 and the rectifier 44 on the other. When this relay is energized, direct current -l danger signal 69. I

lamps to the wire 59 are clearly shown in flows from battery 10 over wires 12, 13, ar

wire 57 4to the safety signal 58. These signals may be lamps or bells .or any other proper devices. The other side of the battery connects to the main return wire 59 by wire 60, the signals53 and 58 connecting directly to this' wire,v 59, while .thel signal 56 connects thereto by the wire- 62, and the signal 54 by wire'63. Should the west-bound track be occupied, relay 8 would be deenergized,yand armature 19 would close these lamp circuits.

If the electron tube or the circuits or parts connected thereto should be inoperative, the relay 41 is cle-energized and current passes from armature 42 over Wire 64 to the wire 65, which connects directly to `the danger signals 66, 67 and 68, the wire 64 extending to The returns from these the diagram. These signalstherefore indicate to the automobile driver whether or not a train is approaching and to the locomotive drivers that the'installation is or is not functioning according vas the signals 53 and 58 or 66 and 68 function as the locomotive passes an insulation 5. But should the installation l cease to function, the lamps 67 and 69 would receive current and thusconstitu'te a permanent warning to automobile drivers. These lamps or signals may be sufciently different from the lamps 54 and 56 to accomplish this purpose. The signals along the track and the signals 54 and 56 are preferably lamps, the signals 53 and 58 being green and the others red. Vhen the engineer sees the green lamp he knows the entire installation is functioning but the red lamp notifies him that the loops 38 and 39 are not energized. The signals 67 and 69 should be very noticeable as they too function when the loops are dead..

The automobile installation.

the tube connects to the wire 75 by wire 82.

and is grounded by wire 83. Plate current normally passes to energized relay 84, wire 85, armature 86, wire' 87, 75 and 82 tothe filament. If this circuit should be broken and relay 84 become de-energized and armature 86 dropped, key 88 may be depressed, completing the circuit by 'way of wire 78, after which the relay will pick up its armature and close its normal circuit.

When the automobile passes over an energized loop 38 or 39, electro-magnetic flux is picked up by the receptor coil 90 which connects to the filament of the tube 73 by means of wires 91 and 83 and to the grid by wires plate current, sufiiciently so as to prevent the energization of relay 84 which drops its armature.

Current now flows from battery 74 over switch 76, wires and 87 armature 86 and wires 97 and 80 to the horn- 79 which -sounds and signals to the driver the approach of a trainen-one of the tracks. The horn will continue to sound until the resetting key 88 .92 and 93, connected by the condenser 94 is depressed. rIhe loops 38 and A39 and the I roadside wires 31 and 35 may be covered with'an insulationl99 which will not be affected by the concrete of the roadway 100 in which'these wires vmay be embedded.

In Fig. 3, a more elaborate automobile installation is shown diagrammatically. The relay 84 is provided with a second armature 101 which normally closes a circuit to the spark .coil 102 from wires 75 and 87 over wire 103, and opens this circuit whenvthe relay 84 is de-energized. A small dash pot 104 may be 4connected toarmature 101 to steady its movement.

Where such construction is possible or desirable, 'an electrically operated brake may be provided to stop'the automobile when'relay 84 is de-energized. The rods 106 extending from the brake mechanism connect to arms 107 on the shafts 108, which also have arms 109 at their inner ends. Links 110 connect these arms to a cross bar 112 attached to the core 113which extends through the solenoid'- 114. Awire 115 connects to the armature 101 in dropped position while a wire 116 connects to the wire' 83 and to the ground.

The details of such a constructionare well known.

Traolcwag/ @mu/its.

In Figure 5, the relay 41 is provided with additional armatures and' 121 which close the circuit between the output coil 30 and the wires 122 and 123 leading to the trackway wires 124 and 125 which connect to the primary windi'ngs 126 of transformers 127 and v128, the secondary .windings 129 of these transformersv connecting to the rails 1-2 and 3--4 respectively. Whend high-frequency Locomotv'fzie installation.

The receptor coil 131 (Fig. 5) is preferably mounted on the leading truck ofthe locomotive near the rails so as to pass through the energized fields of greatest electro-magnetic fluXaround the rails. This-installation comprises two electron tubes 132 and 133, whose filament current is derived from a generator Gr, preferably the headlight generator, and whose plate current is derived from a transformer or dynamotor 134 energized from the generator over wires 135 and 136. The wires 137 and 138 connect the positive side of the dynamotor to the primary winding 139 of the transformer 140, the current passing from this primary winding to the plate of tube 133. A wire 142 extends from wire 137 to relay 143 and wire 144 connects this relay to the plate of tube 132.

,The filaments of these tubes are connected to the wire 135 by Wires 146 and 147, and to the wire 136 by the wire'148. This provides for the heating current. -The plate current passes from the filaments over wires 148 and 136, short wire 149, resistance 150 and wires 151 to the dynamotor. The resistance 150 connects to another resistance 153, -so that. the two may be considered as one of which the coil 150 is thenegative end. The resistance of the part 150 may be one thousand ohms and of the part 153 five thousand ohms, which permits only a few milli-amperes of current to pass, a small amount of current. however being necessary to impress a negative bias of potential on the goods of the tubes 132 and 133.

A negative bias of potential is therefore impressed upon the grid of tube 133 by reason of the'wire 155 engaging the negative resistance 150, this wire connecting to the grid of this tube by wire 156 in which the adjustable condenser 157 is mounted. This negative bias on the grid obstructs to some eX- tent the flow of plate current in this tube, which is a. direcL currlent and therefore places a very low load on this tube and also prevents the core of the normal transformer 140 from becoming saturated. The grid of tube 132 connects to this negative resistance 150 by wire 158 and secondary winding 159 of transformer 140 so that a negative bias of potential will also be normally present in this grid, sufficient tb so obstruct the flow of plate current in tube 132 and in relay 143 .that the armatures 162 and 163 of this relay will normally be down, and current will normally flow from generator G over wire 164 to electro-pneumatic valve 165 which is held closed thereby, wire 166, armature 163 and wire 135 back to the generator.

The receptor circuit embodying the collector coil 131 and condenser 157 responds to the electro-magnetic flux around the track rails and an alternating potential is built up in the receptor circuit, and this potential acts,vv

on the grid of tube 133 and causes its potential to be first less negative and then more negative and this action causes the current in the plate circuit to increase and decrease in unison with the frequency impressed on the grid circuit. So long as constant direct current passes from filament to plate of tube 133, no current is induced in the secondary winding 159 but when varying potential is induced inthe receptor circuit, it changes the bias on the grid of tube 133, the cui-rent passing from filament to plate being increased and decreased, resulting in an alternating current being induced 1n the secondary winding 159.

The positive halves of this alternating current reduce the negative bias of the grid of tube 132 so that current may flow in thc plate circuit of that tube and energize relay 143 so that its armatures 162 and 163 are attracted. Armature 162 closes a circuit between wires 135 and 164 through lamp 168 resulting in a Visible signal thata highway crossing is less than a block ahead. At the same time, armature 163 opens the circuit to electro-pneumatic valve 165 which results in an alarm whistle 169 blowing, giving an audible signal for the same purpose.

The details of construction and the proportions of-resistances, currents and inductances may all be changed by those skilled in the art without departing from the spirit of my invention as set forth in the following claims.

I claim 1.' In a highway crossing, the combination with railway tracks and a highway crossing them, an electric conductor embedded in the highway, a current source, a transformer for transforming the current into radio-frequency current, a circuit between said source and said transformer, a battery connected to the rails, a relay connected to said rails and adapted to be shunted by an oncoming vehicle to cause the closing of the circuit from the current source to sai-d transformer, and a circuit connecting the transformer to the conductor.

2. In a highway crossing, the combination with railway tracks and a highway crossing them, a conductor embedded in the highway, a current source, a transforn'ier for transforming the current into radio-frequency current, a circuit between said source and said transformer, a source of electric energy connected to the rails, a distance from the highway, a relay connected to said rails a lesser distance from the highway and adapted to be cle-energized by an oncoming vehicle passing said battery to cause thc vlosing of the circuit from the current source to said transformer, a circuit connecting the transformer to the highway conductor, a roadside signal along the highway a distance from the track, and a circuitbetween said current source to said signal adapted to be closed when said relay is short circuitedr 3. In a highway crossing, the combination with railway tracks and a highway crossing them, a loop embedded in the highway, a currenty source, a transformer for transforming the ciirrent into radio-frequency current, a circuit, between said source and said transformer, a battery connected to the rails, a relay connected to said rails and adapted to be shunted by an oncoming train to cause the closing of the circuit from the current source to said transformer, a circuit connecting the transformer to the highway loop, a pair of signals along the highway a distance from the track, and normally open circuits between said current source and said signals, and means to close a selected circuit when said relay is de-energized.

4. In a highway crossing, in combination with track'rails and a conductor embedded in the highway a distance from the rails, an

installation for propagating radio-frequency electro-magnetic flux in said conductor and a current source therefor, and means controlled by the presence of a Vehicle on the rails within a predetermined distance from said crossing to cause the operation of said propagating means, and a signal along the highway a distance from said crossing, and means to cause the iow of an operating current to said signal yyhen said propagating means becomes operaive. I

5. In a highway crossing, in combination with track rails and a loop embedded in the highway a distance from the rails, an installation for propagating radio-frequency electro-magnetic iuX in said loop and a current source therefor, means controlled by the presence of avehicle on the rails within a predetermined distance from said crossing to cause the operation of said propagating means, and conductors connecting said propagating vmeans to said track rails.

6. In a highway crossing, in combination with track rails and a loop embedded in the highway a distance from the rails, an installation for propagating electro-magnetic flux in said loop and a current source therefor, means controlled by the presence of a vehicle on the rails within a vpredetermined distance from said crossing to cause the operation of said propagating means, pairs of signal lamps positioned along the rails and the highway v on both sides ofthe crossing a distance from the crossing, circuits from said current source to each lamp, the circuit to one lamp of each pair being normally open and to the other normally closed, and means to reverse such conditions upon the operation of said propagating means.

7 In combination with a loop in a highway adapted to be charged with electro-magv audible signal on said vehicle, a current source v and a circuit therefrom to said signal, a relay and an electron tube whose plate circuit normally energizes said relay to hold the signal circuit open, and an oscillating ,circuit between said receptor coil and the grid of said tube to impress a negative bias of potential thereon to interrupt the plate circuit and thereby cause the signal circuit to be closed.

8. In combination with a loop in a highway adapted' to be charged with electro-ma etic iux, a rece torcoil mounted on a Vehic e and adapted to e affected by said flux, an audible signal on said Vehicle, a current source and a circuit therefrom to said signal, a relay and an electron tube whose plate circuit normally energizes said relay to hold the signal circuit open, an oscillating circuit between said receptor coil and the grid of said tube to impress a negative bias of potential thereon to interrupt the plate circuit and thereby cause the signal circuit to be closed, and means for opening the ignition circuit of the vehicle engine' upon the interruption of said plate current. v

9. I n combination with a loop in a highway adapted to be charged with electro-magnetic flux, a receptor coil mounted on a Vehicle and adapted to be affected by said iix, an audible signal on said yehicle, a current source and a circuit therefrom to said signal, a relay and an electron tube whose plate circuit normally energizes said relay to hold the signal circuit open, an oscillating circuit between said receptor coil and the grid of said tube to impress a negative bias of potential thereon to interrupt the plate circuit and sov thereby cause the signal circuit to be closed, 3

an electro-magnetically operated brake for the vehicle, and means to cause the application of said brake upon the interruption of sai-d plate current.

10. In combination with a loop in a highway adapted to be charged with electro-magnetic flux, a receptor coil on a vehicle and adapted toY be charged with electro-motive force when it passes through said ux, an ignition circuit on said vehicle and a source of ignition current therefor, a relay adapted to control saidl circuit, an electron tube whose plate circuit energizes said relay, and an oscil; lating circuit connecting to said receptor coil to cause the opening of said ignition circuit when said coil receives electro-motive force from said highway loop.

11. In a highway crossing, in combination with track rails and vconductors extending along the highway, aninstallation for propagating electro-magnetic flux in said conductors and a curreiit source therefor, means controlled by the presence of a vehicle on the rails within a predetermined distance from said crossing to cause the operation of said propagating means, signals along the highway, circuits between said current source and said signals, a relay to select said signals and a\circuit between said propagating means and said relay embodying a current rectifier.

12. In a highway crossing, in combination with track rails and a loop embedded in the highwaya distance from the rails, an installation for prop ating electro-magnetic iiux in said loop an a current source therefor, meanscontrolled by the presence of a vehicle on the rails within -a predetermined distance from said crossing to cause the operation of said propagating means, and conductors connecting said propagating means to said track rails, circuits and transformers connectin 'said propagating means to the track rails, an means on t e vehicle responding to the electro-motive force propagated in said track rails to signal the operation of said propagatlng means.

13. In a highway crossing, in combination with track rails and a loop embedded in the highway a distance from the rails, an installation for propagating electro-magnetic flux in said loop and a current source therefor, means controlled by the presence of a vehicle on the rails within a predetermined distance from said crossing to cause the operation of said propagating means, and conductors connecting said propagating means to said track rails, circuits and transformers connecting said propagating means Ito the track rails, and means on the vehicle responding to the electro-motive force propagated in said track rails to signal the operation of said propagating means, said means on the vehicle comprising` visual and audible signals and-a current source to cause their operation.

THOMAS E. CLARK. 

